ZT Imaging System for Layered Thin Wall Structures.
Abstract
Phase I demonstrated the feasibility of using a one-sided x-ray backscatter imaging technique called ZT to display very small delaminations, cracks, porosity, and chemical species differences in a variety of objects. Using both supplied carbon composites materials, some with known defects, and custom built phantoms, a series of experiments was performed to measure the sensitivity limits of the ZT technique to the various anomalies. The equipment consisted of ZT imaging system. During the execution of the program, we modified both the focussing collimator, the detectors and the X-ray beam scanning mechanism were modified to observe the differences in image quality caused by parametric changes in these items. Delaminations as small as 127 microns (0,005 in.) deep and 0.05 in. in diameter were imaged with the laboratory system. In the porosity phantom, holes as small as 787 microns in diameter were visualized. Our density investigations showed the ability to detect density differences as small as 2%. Also uncovered during the density experiments was the sensitivity of ZT to chemical species variations. A mathematical model is constructed which accurately predicts total system performance, including the backscatter process and the human detection probability.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1988
- Accession Number
- ADA195466
Entities
People
- P. J. Bjorkholm